(DataFlex) PC/SC Wait for Smart Card Status Change (Inserted, Removed from Reader, etc.)

See more SCard Examples

Demonstrates how to synchronously wait for a status change, such as for a smart card to be inserted into a reader, or removed from a reader.

Note: This functionality was introduced in Chilkat v9.5.0.87.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoScard
    Boolean iSuccess
    Variant vJson
    Handle hoJson
    String sName
    Variant vSbState
    Handle hoSbState
    Integer i
    Integer iCount_i
    Variant vStReaders
    Handle hoStReaders
    Integer iNumReaders
    Variant vJson2
    Handle hoJson2
    Boolean iChanged
    String sState
    String sAtr
    Integer iNumChanged
    String sTemp1
    Boolean bTemp1

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    Get Create (RefClass(cComChilkatSCard)) To hoScard
    If (Not(IsComObjectCreated(hoScard))) Begin
        Send CreateComObject of hoScard
    End

    // First establish a context to the PC/SC Resource Manager
    Get ComEstablishContext Of hoScard "user" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoScard To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // First we'll examine the state of all connected readers to see which have smartcards already inserted..
    // Get JSON containing information about the smartcards currently inserted into readers.
    // This also includes information about USB security tokens.
    Get Create (RefClass(cComChilkatJsonObject)) To hoJson
    If (Not(IsComObjectCreated(hoJson))) Begin
        Send CreateComObject of hoJson
    End
    Get pvComObject of hoJson to vJson
    Get ComFindSmartcards Of hoScard vJson To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoScard To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // When writing this example, I have 3 smart card readers plugged into my system.
    // One of them has a smart card inserted.
    // Here's the JSON returned by FindSmartcards...

    // {
    //   "reader": [
    //     {
    //       "name": "Alcor Micro USB Smart Card Reader 0",
    //       "state": "empty"
    //     },
    //     {
    //       "name": "Generic Smart Card Reader Interface 0",
    //       "state": "present",
    //       "vendorName": "Generic",
    //       "serialNumber": "3230303730383138303030303030303030",
    //       "systemName": "Generic Smart Card Reader Interface 0",
    //       "card": {
    //         "atr": "3BFC180000813180459067464A00641606F2727E00E0",
    //         "windows": {
    //           "miniDriver": "tagliov70px.dll",
    //           "cryptoProvider": "Microsoft Base Smart Card Crypto Provider",
    //           "keyStorageProvider": "Microsoft Smart Card Key Storage Provider"
    //         }
    //       }
    //     },
    //     {
    //       "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
    //       "state": "empty"
    //     }
    //   ]
    // }

    Set ComEmitCompact Of hoJson To False
    Get ComEmit Of hoJson To sTemp1
    Showln sTemp1
    Showln " "

    // We can iterate over the JSON to find the readers with a smart card already inserted..

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbState
    If (Not(IsComObjectCreated(hoSbState))) Begin
        Send CreateComObject of hoSbState
    End

    Move 0 To i
    Get ComSizeOfArray Of hoJson "reader" To iCount_i
    While (i < iCount_i)
        Set ComI Of hoJson To i
        Get ComStringOf Of hoJson "reader[i].name" To sName

        Send ComClear To hoSbState
        Get pvComObject of hoSbState to vSbState
        Get ComStringOfSb Of hoJson "reader[i].state" vSbState To iSuccess

        Get ComContains Of hoSbState "present" True To bTemp1
        If (bTemp1 = True) Begin
            Showln sName " has a smart card inserted."
        End
        Else Begin
            Showln sName " does not have a smart card inserted."
        End

        Move (i + 1) To i
    Loop

    Showln " "

    // Now let's begin the code to wait for a change (where a smart card gets inserted or removed)

    // Get the list of all readers.
    Get Create (RefClass(cComChilkatStringTable)) To hoStReaders
    If (Not(IsComObjectCreated(hoStReaders))) Begin
        Send CreateComObject of hoStReaders
    End
    Get pvComObject of hoStReaders to vStReaders
    Get ComListReaders Of hoScard vStReaders To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoScard To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Show the reader names..
    Get ComCount Of hoStReaders To iNumReaders
    Move 0 To i
    While (i < iNumReaders)
        Get ComStringAt Of hoStReaders i To sTemp1
        Showln i ": " sTemp1
        Move (i + 1) To i
    Loop

    // Sample output from the above loop.
    // 0: Alcor Micro USB Smart Card Reader 0
    // 1: Generic Smart Card Reader Interface 0
    // 2: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
    // 

    // Synchronously wait 30 seconds for a card to be inserted or removed from any of the above readers.
    Get Create (RefClass(cComChilkatJsonObject)) To hoJson2
    If (Not(IsComObjectCreated(hoJson2))) Begin
        Send CreateComObject of hoJson2
    End
    Get pvComObject of hoStReaders to vStReaders
    Get pvComObject of hoJson2 to vJson2
    Get ComGetStatusChange Of hoScard 30000 vStReaders vJson2 To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoScard To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln " "

    // Let's see what happened...
    Set ComEmitCompact Of hoJson2 To False
    Get ComEmit Of hoJson2 To sTemp1
    Showln sTemp1
    Showln " "

    // This is what json2 contains.
    // A card was inserted into the reader named "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0"
    // The "numChanged" indicates that one reader's status changed.  
    // The "changed":true indicates the reader that changed.   The state is now "present".

    // {
    //   "numChanged": 1,
    //   "reader": [
    //     {
    //       "name": "Alcor Micro USB Smart Card Reader 0",
    //       "changed": false,
    //       "state": "empty"
    //     },
    //     {
    //       "name": "Generic Smart Card Reader Interface 0",
    //       "changed": false,
    //       "state": "present",
    //       "atr": "3BFC180000813180459067464A00641606F2727E00E0"
    //     },
    //     {
    //       "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
    //       "changed": true,
    //       "state": "present",
    //       "atr": "3BDF96FF8131FE455A018048494443313158587300011B09"
    //     }
    //   ]
    // }

    // Find the reader that changed...

    Get ComIntOf Of hoJson2 "numChanged" To iNumChanged
    Showln "number of readers with a changed state: " iNumChanged

    Move 0 To i
    Get ComSizeOfArray Of hoJson2 "reader" To iCount_i
    While (i < iCount_i)
        Set ComI Of hoJson2 To i
        Get ComBoolOf Of hoJson2 "reader[i].changed" To iChanged
        If (iChanged = True) Begin
            Get ComStringOf Of hoJson2 "reader[i].name" To sName
            Get ComStringOf Of hoJson2 "reader[i].state" To sState

            Showln "Changed: "
            Showln "    reader name: " sName
            Showln "    new state: " sState

            // If a card is now in this reader, we should have the ATR of the card..
            Get ComHasMember Of hoJson2 "reader[i].atr" To bTemp1
            If (bTemp1 = True) Begin
                Get ComStringOf Of hoJson2 "reader[i].atr" To sAtr
                Showln "    ATR of card inserted into this reader: " sAtr
            End

        End

        Move (i + 1) To i
    Loop

    // The output from the above loop:

    // number of readers with a changed state: 1
    // Changed: 
    //     reader name: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
    //     new state: present
    //     ATR of card inserted into this reader: 3BDF96FF8131FE455A018048494443313158587300011B09

    // Applications should always release the context when finished.
    Get ComReleaseContext Of hoScard To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoScard To sTemp1
        Showln sTemp1
    End



End_Procedure